Fix mem retrieve in SPM test SP

The SPM test SP uses sp_memory_retrieve() incorrectly. The number of
input regions is actually 0, since we're passing an empty "regions"
array. The "regions" array is for getting the output regions from
sp_memory_retrieve(), out_region_count is correctly set to 1.

Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>
Change-Id: Ice00443eea2034cc173e67b5655412e3be3546fd
diff --git a/components/service/spm_test/sp.c b/components/service/spm_test/sp.c
index f20a15d..e80d412 100644
--- a/components/service/spm_test/sp.c
+++ b/components/service/spm_test/sp.c
@@ -492,7 +492,7 @@
 	descriptor.sender_id = msg->args.args64[3] & 0xffff;
 	acc_desc.receiver_id = own_id;
 	acc_desc.data_access = sp_data_access_read_write;
-	res = sp_memory_retrieve(&descriptor, &acc_desc, regions, 1,
+	res = sp_memory_retrieve(&descriptor, &acc_desc, regions, 0,
 				 &out_region_count, handle);
 
 	if (res) {